It is known from the prior art that when handheld tools operated using internal combustion engines are used, such as cutting-off grinders, chainsaws, or the like, the air sucked in by the engine entrains dirt particles, extremely fine dust, or other solids, which results in significant wear of the engine, for example, at the piston and cylinder, or in frequent maintenance intervals of the intake air filter. Oil-impregnated foam filters are used for air filters of this type, for example. These filters do largely prevent dirt particles from reaching the engine, but a strongly contaminated filter also causes the quantity of combustion air to be reduced and thus the output of the engine to decrease. The maintenance intervals which are thus frequently necessary are time-consuming and costly, in addition, these intervals are no longer performed if the frequency is too high, so that the above-mentioned output reduction remains in existence or is even amplified.